1,10-Phenanthroline as an Efficient Bifunctional Passivating Agent for MAPbI3 Perovskite Solar Cells.

Passivation is one of the most promising concepts to heal defects created at the surface and grain boundaries of polycrystalline perovskite thin films, which significantly deteriorate the photovoltaic performance and stability of corresponding devices. Here, 1,10-phenanthroline, known as a bidentate chelating ligand, is implemented between the methylammonium lead iodide (MAPbI3) film and the hole-transport layer for both passivating the lead-based surface defects (undercoordinated lead ions) and converting the excess/unreacted lead iodide (PbI2) buried at interfaces, which is problematic for the long-term stability, into "neutralized" and beneficial species (PbI2(1,10-phen)x, x = 1, 2) for efficient hole transfer at the modified interface. The defect healing ability of 1,10-phenanthroline is verified with a set of complementary techniques including photoluminescence (steady-state and time-resolved), space-charge-limited current (SCLC) measurements, light intensity dependent JV measurements, and Fourier-transform photocurrent spectroscopy (FTPS). In addition to these analytical methods, we employ advanced X-ray scattering techniques, nano-Fourier transform infrared (nano-FTIR) spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to further analyze the structure and chemical composition at the perovskite surface after treatment at nanoscale spatial resolution. On the basis of our experimental results, we conclude that 1,10-phenanthroline treatment induces the formation of different morphologies with distinct chemical compositions on the surface of the perovskite film such that surface defects are effectively passivated, and excess/unreacted PbI2 is converted into beneficial complex species at the modified interface. As a result, an improved power conversion efficiency (20.16%) and significantly more stable unencapsulated perovskite solar cells are obtained with the 1,10-phenanthroline treatment compared to the MAPbI3 reference device (18.03%).

High-Pressure Metathesis of the M1- xPO3+4 xN1-4 x ( x ≈ 0.05) and M0.75PO4 ( M = Zr, Hf) Orthophosphates.

We describe the oxonitridophosphates M1- xPO3+4 xN1-4 x ( x ≈ 0.05) and the isotypic oxophosphates M0.75PO4 ( M = Zr, Hf) obtained by high-pressure metathesis. The structures (ZrSiO4-type, space group I41/ amd (no. 141), a = 6.5335(7)-6.6178(12), c = 5.7699(7)-5.8409(9) Å, Z = 4) were refined from single-crystal X-ray diffraction data, and the powder samples were examined with quantitative Rietveld refinement. Infrared spectroscopy did not indicate the presence of X-H ( X = O, N) bonds. The optical band gaps, between 3.5 and 4.3 eV, were estimated from UV-vis data using the Kubelka-Munk function under assumption of a direct band gap. Temperature-dependent powder X-ray diffraction showed a phase transformation of the M0.75PO4 ( M = Zr, Hf) compounds to ambient pressure polymorphs at 780 (Zr) and 900 °C (Hf). The preparation of the nitrogen containing compounds exemplifies the systematic access to the new class of group 4 nitridophosphates granted by high-pressure metathesis. Moreover, we show that high-pressure metathesis can also be used for the preparation of metastable oxophosphates.

Accessing Tetravalent Transition-Metal Nitridophosphates through High-Pressure Metathesis.

Advancing the attainable composition space of a compound class can lead to fascinating materials. The first tetravalent metal nitridophosphate, namely Hf9-x P24 N52-4x O4x (x≈1.84), was prepared by high-pressure metathesis. The Group 4 nitridophosphates are now an accessible class of compounds. The high-pressure metathesis reaction using a multianvil setup yielded single crystals that were suitable for structure analysis. Magnetic properties of the compound indicate Hf in oxidation state +IV. Optical measurements show a band gap in the UV region. The presented route unlocks the new class of Group 4 nitridophosphates by significantly improving the understanding of this nitride chemistry. Hf9-x P24 N52-4x O4x (x≈1.84) is a model system and its preparation is the first step towards a systematic exploration of the transition-metal nitridophosphates.

Comparison of Von Willebrand factor (VWF) activity VWF:Ac with VWF ristocetin cofactor activity VWF:RCo.

INTRODUCTION: Ristocetin cofactor activity of Von Willebrand factor (VWF:RCo) and the ratio VWF:RCo to its antigen VWF:Ag are used as routine screening to estimate VWF function and to detect types of Von Willebrand disease (VWD) caused by loss of high molecular weight multimers. However, the VWF:RCo test is prone to analytic imprecisions due to various reasons. We compared an assay for VWF activity (VWF:Ac) with VWF:RCo putting emphasis on the ratios to VWF:Ag. MATERIALS AND METHODS: We evaluated 942 samples from 432 patients and evaluated three groups in detail: normal patients (normal multimers, VWF:Ag and VWF:RCo >0.5 U/ml, VWD type 1 excluded; n=258), VWD type 1 (n=76) and acquired Von Willebrand syndrome (AVWS, n=326). In addition, 30 healthy subjects were analysed. RESULTS: VWF:Ac and VWF:RCo correlated well (Pearson´s r=0.96, p<0.01), so did their ratios to VWF:Ag (Pearson´s r=0.82, p<0.01). We calculated the normal range of VWF:Ac/VWF:Ag for healthy subjects as 0.8-1.16. In comparison, the reference range (mean±2std) derived from normal patient samples was 0.73-1.14. The corresponding ranges for VWF:RCo/VWF:Ag came to 0.74-1.23 (healthy) and 0.62-1.25 (normal patients). The ratios showed similar results regarding VWD type 1. The sensitivity for AVWS was higher with VWF:Ac/VWF:Ag than with VWF:RCo/VWF:Ag (97.5% versus 84.7%). CONCLUSIONS: The data suggest that the results obtained with the VWF:Ac assay are comparable to that of the VWF:RCo assay. An AVWS was more reliably detected by VWF:Ac/VWF:Ag. We assume that the VWF:Ac assay could replace VWF:RCo for routine screening for AVWS, especially when prompt evaluation is required.

Expression patterns of adhesion molecules P-selectin, von Willebrand factor and PECAM-1 in lungs: a comparative study in cases of burn shock and hemorrhagic shock.

For comparative examination of the pathological findings in burn shock and hemorrhagic shock, histological and immunohistochemical investigations of the lungs were performed. Histological specimens of 30 cases each were examined by means of immunohistological staining with P-selectin, von Willebrand factor (vWF) and PECAM-1. The results showed statistically significant differences between the two groups. There was strong staining for P-selectin (especially in the lumina of the blood vessels) and vWF (especially in the endothelium of medium-sized blood vessels) in the specimens of burn shock fatalities. In cases of rapid death after exposure to fire the strong expression of adhesion molecules, which are mainly responsible for the initial inflammatory reaction of leucocytes and platelets in burn shock, suggests prompt activation of inflammatory cells in the lung tissue. In cases of hemorrhagic shock, this reaction was much less distinct in the early stages. The same is true of the expression of PECAM-1, which was lower in lungs from burn shock fatalities than in those from hemorrhagic shock fatalities. The low expression of PECAM-1 in burn shock is a clue to the migration/diapedesis of leucocytes into the areas of burn damage. In total, the results of the investigation indicate different pathophysiological processes even in the very early stages of burn shock and hemorrhagic shock.